The Badwater Ultramarathon describes itself as "the world's toughest foot race". It is a 135-mile (217 km) course starting at 282 feet (86 m)[1] below sea level in the Badwater Basin, in California's Death Valley, and ending at an elevation of 8360 feet (2548 m) at Whitney Portal, the trailhead to Mount Whitney. It takes place annually in mid-July, when the weather conditions are most extreme and temperatures over 120 °F (49 °C), even in the shade, are not uncommon. Consequently, very few people—even among ultramarathoners—are capable of finishing this grueling race.

Remember seeing this guy interviewed on one of those Channel 4 let's-pretend-it's-a-serious-documentary-when-really-everyone-knows-it's-a-teenage-wankfest programmes. He was the new crowned European masturbation champion. He'd had something like 8 orgasms in 5 hours (I pondered at the time that I'd have pissed that when I was in my teens - anyhoo). The Wiki page is interesting reading (extract):

Current records - Time records indicate duration (length of time for which a participant masturbated)

2012 San Francisco: The new World Record holder and winner of "Longest Time Spent Masturbating/Male" is Sonny Nash who on May 27th 2012 passed up Masanobu Sato's record by 12 minutes by pleasuring himself for 10 hours and 10 minutes.
The new World Record holder for distance (standing) is Cem Ismail Duzgun who spurted a very impressive 4.22 metres on June 3rd 2012.
NB - All official Masturbate-a-Thon records are witnessed by trained monitors who attest in writing to their veracity, measurement method and equipment